US 5,854,921 A · Stride-based data address prediction structure

Abstract

A data prediction structure is provided for a superscalar microprocessor. The data prediction structure stores base addresses and stride values in a prediction array. The base address and the stride value from a location within the data prediction structure indexed by an instruction address are added to form a data prediction address which is then used to fetch data bytes into a reservation station storing an associated instruction. If the data associated with an operand address calculated by an associated functional unit resides in the reservation station, the clock cycles used to perform the load operation have occurred before the instruction reached the reservation station. Additionally, the base address is updated to the address generated by executing an instruction each time the instruction is executed, and the stride value is updated when the data prediction address is found to be incorrect.

Claims8

Dependent claims

A method for predicting a data address which will be referenced by a plurality of instructions when said plurality of instructions are fetched, comprising:

generating a data prediction address from a base address and a stride value during a clock cycle in which a data prediction counter indicates that said base address and said stride value are valid, wherein said base address, said stride value, and said data prediction counter are stored in a prediction array;
fetching data associated with said data prediction address from a data cache;
storing said data within a plurality of reservation stations;
updating said prediction array with a new base address during a second clock cycle in which a second data address is generated by executing said plurality of instructions;
incrementing said data prediction counter during said second clock cycle if said data prediction address is correctly predicted;
and
updating said prediction array with a new stride value during said second clock cycle if said data prediction counter indicates that said stride value is invalid.

4 more elements

Dependencies are inferred from the claim text.

Stride-based data address prediction structure

Life of this patent

Stride-based data address prediction structure

Life of this patent

Abstract

Claims8